NEWPORT, R.I. -- Briefed on comments made by a somewhat disgruntled Glen Davis during Media Day, Celtics coach Doc Rivers brushed aside Davis' concern about not having a defined role and sent a firm message back about what he can expect this season.

"No, I'm not even worried about Glen Davis," Rivers said when asked if he had a conversation with the player. "I think he's living up to [his nickname of 'Big Baby']. I didn't even hear it, someone just told me. I'm not that concerned."

Asked if he could understand why Davis might feel uneasy given the addition of two former All-Stars to the frontcourt, Rivers said he shouldn't and sent a friendly warning shot.

"Let me put it like this: If Baby doesn't know his role by now, he's going to be sitting down a lot," said Rivers. "I'll just leave it that simple."

Rivers suggested he won't pay the situation any more attention than it deserves, figuring that might only encourage Davis or others to sound off again.

"No, I just move on," said Rivers. "I've told him that before: His role has been the same for three years now. It's the same. I think he likes us talking about him. That's Glen."

Davis spent the portion of Boston's first practice open to the media running at the power forward spot with a second unit that most often featured Shaquille O'Neal, Marquis Daniels, Delonte West, and Nate Robinson.

During Monday's Media Day, Davis expressed disappointment in the lack of a defined role during his three seasons in Boston, noting he's been asked to change his style each of the last two seasons and is likely to morph again with the addition of Shaq and Jermaine O'Neal this offseason.

"I don't even know, I gotta find out what my role is," said Davis. "With Rasheed [Wallace] last year, I had to become a center. Now? I don't know. Do I become a [power forward]? Do I go back to playing the 4? We'll see.

"It's difficult because, as a player, you kind of don't understand where [the organization is] going or what they are doing. No matter what I do -- I can play great -- it's still not enough. I'm just here to help the team wherever possible, any way I can. Whenever I find my role, I'll do it to the max, the only way I can."

Rivers seemed to suggest that Davis' role has always been to simply aid the frontcourt off the bench, regardless of what particular position he's in, or what style of play that requires. The Celtics have benefited from Davis' flexibility, most notably during a stellar 2008-09 postseason where he filled in for injured Kevin Garnett.

But after off-the-court troubles derailed his 2009-10 season before it began, Davis struggled to find a role once he returned, especially with the addition of Wallace. Davis averaged 15.8 points, 5.6 rebounds and 1.8 assists per game in the 2008-09 playoffs, but his averages dipped to 6.3 points, 3.8 rebounds, and 0.6 assists in 54 games last season (below even his 2008-09 regular-season numbers).

"It bothers me, but at the same time, I'm a player," Davis, who is in a contract year, admitted Monday. "Put me out on the court and I'll do anything you want me to do. That's the beauty of my position. Throw me out there and I'm going to play. I'm going to go out there and guard Shaq. Throw me out there and I'm gonna guard Rashard Lewis. Put me wherever you want to put me, I'm going to guard whoever you want me to guard. I'm just a basketball player.

"The role I would prefer to play is the role they want me to play."